ChangeLog: November 5, 2018

The World Update: Python 3 and Django 2

In a previous post, we talked the work we’re doing to move to modern versions of Python and Django. We’re calling this the “World Update,” and it’s quite a large and difficult project.

Database Migrations and Django Evolution

Much of the difficulty comes from an incompatibility between how we handle database migrations (using Django Evolution) and how Django handles them (using their built-in migrations support). These aren’t at all compatible, and for many reasons (legacy support and performance), we don’t want to ditch Django Evolution. This has by far been the biggest hurdle to overcome for the World Update.

We’ve been working on this, reworking nearly all of Django Evolution to better utilize migration support in Django, to provide a new set of generic structures for describing database state and modifications, and to (soon) hook into and partly override the migration process to allow both to co-exist.

Progress on this had been steady, and we feel we’re reaching a point where we’ll be able to fully support migrations in Django Evolution.

Djblets and Review Board Work

We now have Djblets working with modern Python 3.x releases and Django 1.6 through 2.1, so we’re in good shape there.

Review Board has a large number of patches in the works to bring Python 3.x and Django 2.1 compatibility. The biggest challenge in Review Board has to do with string type safety. In Python 2.x, Unicode and byte strings are somewhat interchangeable, but there’s a sharp divide in Python 3. We’ve found many cases where we’ve made bad assumptions about string types in Review Board, and are working on both fixing these and adding strict type checks.

World Update Releases

We’re expecting that Review Board 5.0 will require Python 3.5+ and the latest Django 2.x. Administrators will have to make sure they’re running a modern OS with the necessary version of Python, and extension authors will have some updates to perform, but in the end this will be so worth it.

Review Board 4.0 Status

We were initially hoping to release this in August, but that certainly didn’t happen. Too many things came up over this year that took away from the release.

The good news is, DVCS works, and we’re trying to polish up the experience. There’s a few other features we’re also trying to get into 4.0, but once we’re at a point where we feel people can begin safely using DVCS, the beta will start shipping. That will be… soon-ish. We’ll see what happens with the holidays.